Vitamins are essential organic nutrients human Requirement in a matter of minutes. The fat-soluble vitamins are vitamins A, D, E and K. To some extent, this vitamin is different from water-soluble vitamins. This vitamin is found in fatty and oily parts of food. This vitamin is only digested by bile because it does not dissolve in water.

The following sections provide detailed descriptions of each vitamin type.

Vitamin A

Requirement
Vitamin A is produced from two different compounds are converted in the body into vitamin A. In animal food sources, are available in the form of retinol (pro-vitamin A); in plant food sources are in the form of beta-carotene (a substance in the form of yellow-orange color), which is less efficient than retinol for the production of vitamin A. This is why the recommended amount of vitamin A given in the form of retinol equivalents, RE. The recommended amount of vitamin A is 1000 micrograms RE per day for men and 800 micrograms for women.

The main sources
Vegetables and fruits are a carrier for vitamin A the most. Most of the foods that contain vitamin A is a brightly colored (but not all bright colored foods contain vitamin A). Vegetables rich in vitamin A include carrots, sweet potatoes, yellow squash, spinach and melons. Milk, cheese, butter and eggs also contain vitamin A.

Function

Vitamin A is essential for the maintenance of corneal and epithelial cells of the vision. Actual function of the eye is to improve night vision, the ability to restore vision after reflected by a beam of light in the dark.

Vitamin A helps growth and reproduction of bone and teeth. At the time of growth, the bone will experience little decomposition, then stretching before finally rebuilt. Vitamin A is required in the first step, the process of bone breakdown. As you know, children who have deficiencies in vitamin A will not grow well.

In addition, vitamin A also plays a role in the formation and regulation of hormones and helps protect the body against cancer.

Symptoms of deficiency
Vitamin A deficiency is usually accompanied by lack of protein and zinc minerals. Vitamin A can be stored in the body for a year. This means that the symptoms of deficiency does not appear immediately after the cessation of intake of this vitamin. However, if this appears after long periods of time there is no consumption, the symptoms may be very clear and severe.

One of the first symptom is night blindness and decreased function of the cornea. This vitamin deficiency can also prevent the growth of bone, or cause changes in bone shape, forming cracks and damage to the teeth and atrophy tooth-forming cells. Anemia is caused by another. In addition, this deficiency affects the bones and nervous system, and can lead to paralysis.

Toxicity
The human body can easily convert beta-carotene into vitamin A as needed. At the time the amount of vitamin A have been sufficient, beta-carotene is left is left circulating in the body and then released slowly. The only impact is if the excess skin will be yellow, and this is totally harmless.

However, when the pro-vitamin A consumed in excess it will cause serious problems. The amount is more than pro-vitamin A is stored in the liver, and if too much will cause damage to the liver. Others will go into the bone, in which these elements will work to dissolve the bone material, which will eventually lead to other problems, osteoporosis.

Vitamin A poisoning usually happens to someone who uses supplements. Symptoms include nausea, vomiting, abdominal pain, diarrhea and weight loss. Nervous system and muscles may also be affected, causing symptoms such as loss of appetite, irritability, fatigue, insomnia, restlessness, headache and muscle weakness.

Vitamin D

Requirement
Vitamin D is also known as calciferol can be produced by sunlight. This means that vitamin D can be obtained with fixed sunlight exposure regularly, and do not need extra vitamin D. With adequate lighting from the sun (usually about 5 minutes per day, 3 times a week, on the face and arms), the human body can function the same as vitamin D. The RDA for vitamin D is 5 micrograms per day. Although the amount of vitamin D that is formed increases over the skin exposed to sunlight, but sunlight alone can not cause vitamin D to the level of intoxication.

The main sources
Food sources of vitamin D are eggs, liver and fish, as well as milk and margarine fortified with vitamin D.

Function
Vitamin D works on bone mineralization by increasing the absorption of calcium and phosphorus in the digestive system, so that levels in the blood rises. This is done by taking calcium from the bones and by encouraging the retention by the kidneys.

Symptoms of deficiency
Causes of vitamin D deficiency is similar with symptoms of calcium deficiency. Bones can not be hardened. Bones can be weakened as a result of crooked bone weight. Vitamin D deficiency can also cause deformities and pain in the arms and legs, backs, torax (chest cavity) and the pelvis. Vitamin D deficiency also damages the nervous system and muscles, causing muscle spasms.

Toxicity
Excess vitamin D causes an increase in the concentration of calcium in the blood. Calcium can form kidney stones. High calcium levels in the blood can also cause blood vessels to harden, which is very dangerous for the arteries of the heart and lungs and can be fatal. Additional symptoms of vitamin D poisoning are loss of appetite, headache, weakness, fatigue, excessive thirst, irritability and lethargy.

Vitamin E

Requirement
The RDA for vitamin E is 10 mg per day for men and 8 mg per day for women.

The main sources
Vitamin E (also known as tocopherol) is widely available in vegetable and seed oils, which can be found in the form of margarine, salad dressings, and shortenings. Peanut oil and bran oil has the highest concentration of vitamin E. One tablespoon of these sources contain more than the RDA of vitamin E. In contrast, animal fats such as butter and milk contains almost no vitamin E. This is because vitamin E is easily destroyed by heating, so it is better get it from fresh foods.

Function
Like vitamin C, vitamin E is also an antioxidant. Vitamin E helps stabilize cell membranes, regulate and protect the oxidation of vitamin A. In its role as an antioxidant, vitamin E has a major effect on cells, such as red blood cells and white blood cells passing through the lungs.

Symptoms of deficiency
When levels of vitamin E in blood is very low, red blood cells can be divided. This process is called hemolysis of erythrocytes and can be avoided by vitamin E. Vitamin E deficiency can result in nervous system and causes muscle weakness, difficulty walking and pain in the calf muscle. Unsaturated fats found in cell membranes that cover every type of cell in the body, then the state of severe vitamin E deficiency can affect every organ system. Impact prior to the turnover of cells that often occur.

Toxicity
Poisoning can occur if excessive consumption, but this does not easily occur as in vitamins A and D. Symptoms include headache, weakness, fatigue, dizziness and abnormal vision.

Vitamin K
Vutamin K is also known as phylloquinone or naphthaquinone

Requirement
Most sources of vitamin K in the body is synthesized by bacteria in the digestive system. Sources of vitamin K in foods are liver, green vegetables are leafy, cabbage and milk.

The main sources
Digestive systems of humans contains bacteria that can synthesize vitamin K, which is partially absorbed and stored in the liver. The body need to get extra vitamin K from food. Antibiotics, which are often used to cure the infection, can destroy the bacteria that produce vitamin K, although for a temporary period. For patients who undergo antibiotic treatment, K is a "vitamin" that should be consumed. Green leafy vegetables are good sources of vitamin K.

Function
Vitamin K is an essential requirement for the synthesis of several proteins including the clotting of blood. Vitamin K is also needed for bone formation.

Symptoms of Deficiency
If vitamin K is not contained in the body, blood can not clot. This can cause hemorrhagic diseases. However, vitamin K deficiency is rare: only infants who easily experience it. This is because the digestive system of a newborn baby is sterile and does not contain bacteria that can synthesize vitamin K, breast milk contains only small amounts of vitamin K. For that baby is given a number of vitamin K at birth.

Toxicity
Toxicity of vitamin K occurs only in people who receive water soluble vitamin K replacement. The symptoms are a red blood cell hemolysis, jaundice and brain damage.